A test for occult blood is known. The method utilizes the oxygen-releasing reaction between hydrogen peroxide and hemoglobin to effect a color change in gum guaiac or benzidine derivatives.
The presence of occult blood in feces may be significant because it may indicate a digestive tract disorder, including colon cancer. Positive identification of blood in the feces usually indicates the need for determining the cause by specific testing.
Despite the opportunities and ease of testing for occult fecal blood, such testing is not routinely done. To perform a test, a doctor would need to carry a source of indicator, hydrogen peroxide and a dropper. The patient may be squeamish about the test. In some cases, slides are given to the patient with instructions to smear his own stool.
The need continues for a portable test for occult blood, all components of which are self-contained and which can be performed by a physician discreetly during routine examination in an examination room or while making hospital rounds.